Phonology of modern Lhasa Tibetan
The following summarizes the sound system of the dialect of Tibetan spoken in Lhasa, which is the most influential variety of the spoken language Vowels Tournadre and Sangda Dorje describe eight vowels in the standard language: Three additional vowels are sometimes described as significantly distinct: or , which is normally an allophone of ; , which is normally an allophone of ; and (an unrounded, centralised, mid front vowel), which is normally an allophone of . These sounds normally occur in closed syllables; because Tibetan does not allow geminated consonants, there are cases where one syllable ends with the same sound as the one following it, with the result that the first is pronounced as an open syllable but retains the vowel typical of a closed syllable. For instance, zhabs (foot) is pronounced and pad (borrowing from Sanskrit padma, lotus) is pronounced , but the compound word, zhabs pad is pronounced . This process can result in minimal pairs involving sounds that are otherwise allophones. Sources vary on whether the phone (resulting from in a closed syllable) and the phone (resulting from through the i-mutation) are distinct or basically identical. Phonemic vowel length exists in Lhasa Tibetan, but appears in a restricted set of circumstances. Assimilation of Classical Tibetan's suffixed vowels—normally ‘i (འི་)—at the end of a word produces a long vowel in Lhasa Tibetan; this feature is sometimes omitted in phonetic transcriptions. In normal spoken pronunciation, a lengthening of the vowel is also frequently substituted for the sounds and when they occur at the end of a syllable. The vowels , , , , and each have nasalized forms: , , , , and , respectively. Historically, this results from a syllable-final , such as , , etc. In some unusual cases, the vowels , , and may also be nasalised. Tones The Lhasa dialect is usually described as having two tones: high and low. However, in monosyllabic words, each tone can occur with two distinct contours. The high tone can be pronounced with either a flat or a falling contour, while the low tone can be pronounced with either a flat or rising-falling contour, the latter being a tone that rises to a medium level before falling again. It is normally safe to distinguish only between the two tones, because there are very few minimal pairs which differ only because of contour. The difference only occurs in certain words ending in the sounds m or ŋ; for instance, the word kham ( , "piece") is pronounced with a high flat tone, while the word Khams ( , "the Kham region") is pronounced with a high falling tone. In polysyllabic words, tone is only important in the first syllable. Consonants Notes: # The unaspirated stops , , , and typically become voiced in the low tone, being pronounced , , , and , respectively. These sounds are regarded as allophones. By a similar process, the aspirated stops , , , and are typically lightly aspirated in the low tone. The dialect of upper social strata in Lhasa does not use voiced stops in the low tone. # The alveolar trill ( ) is in complementary distribution of the alveolar approximant ; therefore, they are treated as one phoneme. # The voiceless alveolar lateral approximant resembles the voiceless alveolar lateral fricative found in languages such as Welsh and Zulu and is sometimes transcribed }}. # The consonants , , , , , and may appear in syllable-final positions. The Classical Tibetan final is still present, but its modern pronunciation is normally realized as a nasalisation of the preceding vowel, rather than as a discrete consonant (see above). Note that is not pronounced in the final position of a word, except in highly formal speech. Also, syllable-final and are often not clearly pronounced, but instead realized as a lengthening of the preceding vowel. The phonemic glottal stop appears only at the end of words in place of an , , or which were pronounced in Classical Tibetan but have since been elided. For instance, the word for Tibet itself was Bod in Classical Tibetan and is now pronounced in the Lhasa dialect.